In the treatment of storm water, it is necessary to remove various undesirable elements and components, such as bacteria, oil, metals, nutrients, trash and a number of other solids. Many of the pollutants bond to the finer sediment and which is the reason many regulatory agencies now focus on total suspended solids (TSS) as a criteria for design/approval of stormwater quality measures.
To that end, the Clean Water Act requires some stormwater quality treatment for all new developments over 0.5 acres in size. Many types of equipment and processes have been suggested for dealing with this problem.
One of the difficulties in the removal of such materials from stormwater is the need to take into account different flows of that water. For example, under normal conditions, there may be a steady, relatively low flow of water that passes through the treatment facility, while at other times, there is a heavy storm with rapidly rising flow rates and, therefore, the stormwater treatment facility needs to also be able to treat that high flow of water.
The treatment devices need to be capable of removing debris and undesirable liquids, such as oil that floats on the surface of the water under both flow conditions efficiently and at a low cost of the equipment.
Accordingly, there have been various stormwater treatment devices that provide for the conveyance of the high flows and the low flows by creating a bypass for the high flow of the water so that the high flow does not pass through the same treatment facilities as the low flow of water. In such treatment facilities, however, the high flow that bypasses the low flow treatment chambers is not normally treated to remove both floating and non-floating materials.
One of such stormwater treatment devices is shown and described in U.S. Pat. No. 4,985,148 of Monteith. In the stormwater treatment device of that patent the bypass stream of the high flow water is not treated for the removal of floating and non-floating materials. Accordingly, while the Monteith system does consider conveyance for the high flow stream of water from a heavy runoff, that bypass water simply passes though the apparatus without any treatment and thus undesirable floatable and non-floatable materials in the high flow stream can be conveyed downstream without being removed.
Thus, there is a desire for an efficient and cost effective means for trapping debris in storm water that overcomes the difficulties of the aforedescribed stormwater treatment devices and yet which is effective at trapping both floating and non-floating particulate matter. Such an apparatus should be simple in its design and be able to be produced at low cost.
The device should be flexible in varying field conditions, i.e., able to satisfy varying size and height requirements and be able to connect efficiently to the non-linear junction points that inevitably occur in piping systems.